Subwoofer placement - does it matter?

Placement makes a huge difference that is easily measured with a real time analyzer and measurement microphone.  I did a bunch of that when I was younger and differences can be huge.  Resonances build up and the sub in a certain spot will excite certain resonances way more than in another spot.  You can just put on some bass heavy content and walk around the room and notice huge differences.  Some places will be very bass shy but if you stick your head near a corner the bass will be much stronger.  It's not subtle.

@emergingsoul  You can measure it if you want to understand it.  bass is difficult to get right.  In my opinion the way to go is main speakers that have a slow drop in response starting at a fairly high frequency.  Mains that are flat to 20hz are likely to cause all sorts of bass problems when they are placed in the best position for the rest of the frequency spectrum. Full range mains are a terrible idea. And you almost certainly want multiple subs.